Various rotor designs for PCRs have been suggested over the year. One rotor design has been suggested in U.S. Pat. No. 7,625,532 where in particular FIGS. 4 and 5 show details of the suggested rotor.
Referring now to FIG. 4 of U.S. Pat. No. 7,625,532 the rotor drum 37 provides a suitable surface onto which the blades 28 are attached. The blades 28 are bolted to the rotor drum 37 at 45 degrees intervals such that there are eight equally spaced blades 28 positioned around the rotor drum 37. Each blade 28, which in FIG. 4 extends substantially the whole length of the reaction vessel 20, is mounted at a first end thereof onto the rotor drum 37 via a mechanical support 28a. In FIG. 5 the blades 28 are axially spaced along the length of the reaction vessel 20.
Each blade 28 has a free second end which is spaced from the internal wall of the reaction vessel 20 forming the ablative surface 20a by about 1 mm or less. Between its first and second ends each blade 28 has a curved front surface 28b. In the shown embodiment the blades 28 are permanently fixed at a predetermined angle to give a fixed clearance from the ablative surface 20a. In a modification of the shown embodiment, the blades may be provided with calibration screws which allow for adjustment of the blade angle and/or clearance, cf. column 3, last sentence. However, during operation of the PCR the blade angle and/or clearance is fixed.
It is a disadvantage of the arrangement shown in U.S. Pat. No. 7,625,532 that the fixation of the blade angle and/or clearance, i.e. the fixed position of the blades 28 relative to the ablative surface 20a, allows treatment of biomasses with only a certain particle size. In the arrangement shown in U.S. Pat. No. 7,625,532 small particles will not be pressed against the ablative surface 20a. Moreover, large particles may be stocked or wedged between the blades 28 and the ablative surface 20a.
It may be seen as an object of embodiments of the present invention to provide a rotor for a PCR which is capable of being operated at low rotational speeds.
It may be seen as a further object of embodiments of the present invention to provide PCR which is capable of treating a solid feed with different particle sizes into char, tar and gasses.